/Engine/Source/Editor/UnrealEd/Public/Kismet2/BlueprintEditorUtils.h
Cleanses a name of invalid characters and replaces them with '_'. See UE_BLUEPRINT_INVALID_NAME_CHARACTERS for invalid characters.
static void ReplaceInvalidBlueprintNameCharacters ( [FString](API\Runtime\Core\Containers\FString) & InBaseName )